Shoulder Bump Gauge
- Thread starter 1340
- Start date
shoot_to_kill
CGN Regular
- Location
- Luskville quebec
I have the hornady one, it works well. I got it at cabelas
If you ever have a new barrel fitted, you can have one made from the wasted muzzle end of the barrel.
When a barrel is made they lap from breach to muzzle in ever longer strokes. This creates a slight taper to the barrel, which is good.
The problem is they don't get all the way to the end of the barrel so the first inch or two at the muzzle is always cut off and discarded.
You can have your barrel fitter square off this wasted part and spin it up and run your chambering reamer into it just enough to bury the shoulder.
Now you have a shoulder bump gage and a sample of your chamber that you can also use to set bullet seating depths without needing the rifle.
Dan Dowling did this for me when he chambered a rifle for me many years ago when he did my 6x47L and now I make sure its done every time I chamber a new barrel.
Just make sure its long enough that bullets don't protrude out the front of it.
If you don't have a piece of your barrel, you can always drill a pilot hole into a piece of nicely squared off cold rolled steel and run your chambering reamer into that. (Assuming you have your own reamer.)
When a barrel is made they lap from breach to muzzle in ever longer strokes. This creates a slight taper to the barrel, which is good.
The problem is they don't get all the way to the end of the barrel so the first inch or two at the muzzle is always cut off and discarded.
You can have your barrel fitter square off this wasted part and spin it up and run your chambering reamer into it just enough to bury the shoulder.
Now you have a shoulder bump gage and a sample of your chamber that you can also use to set bullet seating depths without needing the rifle.
Dan Dowling did this for me when he chambered a rifle for me many years ago when he did my 6x47L and now I make sure its done every time I chamber a new barrel.
Just make sure its long enough that bullets don't protrude out the front of it.
If you don't have a piece of your barrel, you can always drill a pilot hole into a piece of nicely squared off cold rolled steel and run your chambering reamer into that. (Assuming you have your own reamer.)
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Munkey1973
CGN frequent flyer
- Location
- Regina, SK
I am trying to avoid sounding like a dink but why should it matter if the gauge is made from stainless steel instead of aluminum ?
I have a a Hornady, and I would think that it would be not more durable and repeatable/accurate if it were made from stainless.
It would most likely yield the same results as aluminum.
This sounds interesting.. but I could imagine that it would cost (at the very very least) twice as much as buying one commercially made?
Well maybe. Once a guy gets serious about target shooting its not long before he is ordering his own chambering reamer. Once you have it, you have already solved half the problem.
All you really need at that point is a drill press and a nice piece of steel... even aluminum would work.
As I said earlier... Now you have a full chamber match to set your bullet seating depth as well as measure shoulder bump.
At this point, cost doesn't really factor in. But its not expensive once you have your own chambering reamer. Its not twice the cost of a chambering job... Not even close.
As I said earlier Dan Dowling did it for for me, but I didn't ask him to... He just did it for free because its the right thing to do. Dan is the inventor of the 6 Dasher if you didn't know that. One of them anyway.
Munkey1973
CGN frequent flyer
- Location
- Regina, SK
Again, I'm not discrediting what you are saying... in fact I am quite intrigued.
Its just that for probably a vast majority of us on the forum, this in not an option.
I'm only about 6 seasons in the F T/R scene.
The upcoming season will be my 3rd season with a quality custom built 308 (after giving up with an off-the-shelf 223 and consistently placing near the bottom of every match).
When I was planning the build with my gunsmith, he tried to get me to order my own custom reamer.
After ordering the action, barrel, and other parts, I had already exceeded the budget so I just had him use the 308 US Palma Team reamer he already had at his shop.
On the next custom build, I might buy the reamer to own for evermore.
I'd be keen on this idea of yours but more importantly having the ability of maybe making my own seating for an arbour press.
I was on your site, but couldn't find bump gauges.
257Roberts
CGN frequent flyer
- Location
- Peterborough ON
I have made my own similar to the Sinclair tools.
It references the shoulder to case head length including the tool as well.
Using Redding competition shell holders I can bump the shoulder back within .002".
It references the shoulder to case head length including the tool as well.
Using Redding competition shell holders I can bump the shoulder back within .002".
Barrels are like brake pads on your car. Its a consumable item that competitive shooters know they will replace regularly. Maybe when you are just getting a barrel it wont hurt so much. We have all been there and eventually want to control the chamber to our specific needs and to do that we need our own reamer. In time the sting of the original build will pass and when you find yourself with a few bucks you can order one. They aren't expensive really, when not bundled into some larger purchase.
You can even use your chambering reamer to make your own shoulder bump die. You can buy a die blank and run the reamer into it. Then have it hardened. That way the die will not size the side wall... just bump the shoulder.
Bob Galloway did this for me and my 6mm Creedmoor. Fantastic little tool
With the Hornady type cartridge case headspace gauge you only need this one gauge for all calibers. If you get a Whidden type enclosed gauge it is only good for one caliber.
I have a RCBS Precision Mic for the .308 and the Hornady gauge and prefer the Hornady gauge. Yes the Hornady gauge is made of aluminum and "might" wear from spinning the case. "BUT" you zero the gauge with a fired case and zero is the starting point for setting your die up for the shoulder bump. Meaning even if the aluminum does wear down you can still set the gauge to zero and compensate for any wear.
Below I'm measuring a "fired" Lake City 5.56 case and then set the die up for .003 shoulder bump for my AR15 rifles. I spin the case to get the case to center it and get the shortest measurement. I had my Hornady gauge for over 12 years and have a slight shiny ring where the shoulder touches the gauge from spinning/rotating the case. You then zero the vernier caliber and start checking the resized cases for the proper amount of shoulder bump.
Below a Colt Field gauge at 1.4736
Below the same field gauge in my adjusted/tweaked Hornady gauge. You can adjust the gauge by adjusting the air gap between the red and silver sections of the gauge.My gauge read .011 less than the headspace gauge so I put a .011 feeler gauge between the two sections and then locked them down. This told me within .001 what my actual headspace was for my AR15 carbine.
Below my RCBS Precision Mic that can only measure .308 and .243 cases. Meaning these types of gauges do not measure as many calibers cases as the Hornady gauge does. On top of this the RCBS gauge is not calibrated, my gauge read .002 less than my GO gauge.
I have a RCBS Precision Mic for the .308 and the Hornady gauge and prefer the Hornady gauge. Yes the Hornady gauge is made of aluminum and "might" wear from spinning the case. "BUT" you zero the gauge with a fired case and zero is the starting point for setting your die up for the shoulder bump. Meaning even if the aluminum does wear down you can still set the gauge to zero and compensate for any wear.
Below I'm measuring a "fired" Lake City 5.56 case and then set the die up for .003 shoulder bump for my AR15 rifles. I spin the case to get the case to center it and get the shortest measurement. I had my Hornady gauge for over 12 years and have a slight shiny ring where the shoulder touches the gauge from spinning/rotating the case. You then zero the vernier caliber and start checking the resized cases for the proper amount of shoulder bump.
Below a Colt Field gauge at 1.4736
Below the same field gauge in my adjusted/tweaked Hornady gauge. You can adjust the gauge by adjusting the air gap between the red and silver sections of the gauge.My gauge read .011 less than the headspace gauge so I put a .011 feeler gauge between the two sections and then locked them down. This told me within .001 what my actual headspace was for my AR15 carbine.
Below my RCBS Precision Mic that can only measure .308 and .243 cases. Meaning these types of gauges do not measure as many calibers cases as the Hornady gauge does. On top of this the RCBS gauge is not calibrated, my gauge read .002 less than my GO gauge.
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